養殖用水處理技術與節水養殖技術之開發，並將養殖水及排放廢水再予利用，可減輕養殖業對環境的充擊，此為台灣養殖業永續發展的重要課題。本研究結合人工溼地技術應用於循環水養蝦，建立了一實場規模(large scale)之循環水系統，探討自由水層溼地（free water surface flow wetland，FWS）串聯另一個表層下溼地（subsurface flow wetland，SSF）溼地對循環水之處理效能及對養殖水質維護之影響。
實場規模循環水系統中，FWS-SSF溼地之水力負荷平均操作於1.88±0.49 m/d，溼地可同時去除循環水中各項污染物，包括BOD5 (37%)、SS(55%)、NH4-N(69%)、NO2-N(80%)，濁度(98%)。可能因高水力負荷之影響，溼地對NO3-N及PO4-P無明顯的去除。大體上，循環水系統養殖池水中各污染物濃度經溼地處理後循環水及養殖池水之各項水質均可達一般循環水養殖水質要求。
養殖過程中，循環水系統在無須換水的條件下養殖白蝦(Litopenaeus vannamei)，放養密度採1000尾/m2之高密度養殖，養殖期間餌料之投放量則依據蝦體大小及攝食狀況調整，每日餵飼2～4次，至養殖達第165天時總投餌量累計達約263.52 kg。蝦體初重為0.05g，養殖達第137天時蝦體大小平均可達6.98g，全期蝦子平均生長速率約0.05 g/d。
人工溼地建設中無須安置機械設備，在養殖過程中無須曝氣、無須時常排泥、操作簡單，因此為循環水養殖中效率高、低成本、省能源、維護簡單的淨水技術‧ Water treatment and water-saving technologies are helpful for sustaining aquaculture development in Taiwan. In this study, the constructed wetlands (CWs) were integrated into the recirculating aquaculture system (RAS) so as to regulate the water qualities for culture of white shrimp (Litopenaeus vannamei). A commercial scale RAS was built to demonstrate the performance of the CWs in treating the recirculating wastewater and to examine the effect of water qualities regulation by the CWs on the shrimp growth.
In the RAS system, a cultivation tank (8 m wide × 8 m long), a settling basin (1 m wide × 1.5 m long), a FWS wetland (1 m wide × 12 m long), a SSF wetland (1 m wide × 15.6 m long), and a wet well (1 m wide × 1 m long) were established and integrated. The FWS-SSF CWs removed simultaneously the major pollutants in the recirculating water under an average HLR of 1.88±0.49 m/d for around 165 days operation. These pollutants included BOD5 (37%), SS (55%), NH4-N (69%), NO2-N (80%), and turbidity (98%). Significant removals of nitrate and phosphate were not observed possibly due to the high HLR operated in large-scale RAS. However, the treated effluent from the FWS-SSF CWs can meet the general water quality guidelines for recirculating fish culture system.
This study concludes that the integrated use of the CWs into the recirculating shrimp culture system can improve qualities of culture environment and consequently increase the shrimp growth. Additionally, CW technology is characterized by the advantages of moderate capital costs, low energy consumption and maintenance requirements, and benefits of increased wildlife habitat.
